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Harvard Forest REU Symposium Abstract 2014

  • Title: Meteorological changes in declining hemlock forests
  • Author: Emily D Keenan (University of Michigan)
  • Abstract:

    Since its appearance in Virginia in the 1950’s, the hemlock woolly adelgid (HWA; Adelges tsugae) has spread to infest Eastern Hemlocks (Tsuga canadensis) along the eastern coast of the United States. These trees are a foundation species throughout many East Coast forests and their decline dramatically alters the forest structure. The study site at the Prospect Hill tract at the Harvard Forest in Petersham, MA is dominated by T. canadensis and is the subject of long-term research. In anticipation of an A. tsugae infestation of the stand more than five years ago, meteorological parameters and fluxes of carbon and water were closely monitored. I expected to see increased levels of photosynthetically active radiation (PAR) in the understory because of the decline in growth of needles and decreasing canopy thickness. This is supported by an increase in PAR at the understory level and a decrease in percentage of light intercepted by the canopy in 2013. Overall these changes will become more dramatic with time as this is the beginning of the decline. Other factors examined were soil moisture, soil temperature and air temperature, but no significant change was found in any as of 2013. Decline of T. canadensis will not only directly affect species composition but also other forest processes in the area. Analyzing the changes that are already occurring can lead to a greater understanding of the problem and what can be expected in the future.

  • Research Category: Invasive Plants, Pests & Pathogens; Large Experiments and Permanent Plot Studies